1. Technical Field
The present invention relates generally to integrated circuits having Back End of Line (BEOL) structures including fuse elements, and more particularly, to a laser fuse deletion process including forming a dielectric cap of known thickness over the fuse.
2. Related Art
Fuses formed within small electronic structures can serve several functions. For example, fuses may be formed within a structure to support higher production yields through redundancy. In other words, particular fuses may be deleted or opened to re-route circuitry along alternate pathways in the event of a failure. Alternatively, fuses may be selectively deleted to form a matrix of opens and shorts unique to that circuit which may easily be recognized by an electrical computer identification system.
Laser fusing processes are typically used to delete specific fuses. During a laser fuse deletion process the fuse structure, including the size, shape and material of the fuse itself, as well as the type and thickness of the material covering the fuse, are of critical importance to the quality of the fuse deletion. Accordingly, it is desirable to optimize any or all of these parameters to enhance the success of the fuse deletion process.
The first general aspect of the present invention provides an electronic structure comprising a substrate including a fuse formed within the substrate; and a first etch-resistant layer over the fuse; and a second etch-resistant layer over the fuse, wherein the second etch-resistant layer is adjacent to the first etch-resistant layer and is between the first etch-resistant layer and the fuse.
The second general aspect of the present invention provides a method of forming a fuse structure, comprising providing a fuse layer having a fuse formed therein; and depositing a lower etch-resistant layer over a surface of the fuse layer; and depositing an upper etch-resistant layer over the lower etch-resistant layer.
The third general aspect of the present invention provides a method of performing a fuse deletion, comprising: providing a substrate including at least one fuse therein, a lower etch-resistant layer over the fuse and an upper etch-resistant layer over and adjacent to the lower etch resistant layer and at least one insulative layer over the upper etch-resistant layer; and removing a portion of the at least one insulative layer above the fuse to the upper etch-resistant layer; and removing a portion of the upper etch-resistant layer above the fuse to the lower etch-resistant layer; and applying a radiant energy source to the fuse until the fuse is deleted.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention.